Physical Landscapes UK: Coastal Landscapes and Processes Flashcards
Coast
Where the land meets the sea
How do waves form?
Wind blows over surface of sea —> friction is created, producing a swell in the water
The size of waves depend on:
- The fetch (how long wave has travelled)
- Strength of wind
- How long wind has been blowing for
Why do waves break?
1) Waves start out at sea
2) As waves approach shore, friction slows base of waves
3) This causes orbit of waves to become elliptical until the crest of the wave breaks over
Constructive waves:
- formed by storms hundreds of miles away
- strong swash + weak backwash
- strong swash brings sediments to build up the beach
- backwash is not strong enough to remove the sediment
- waves are low + further apart
- break gently
Destructive wave:
- formed by local storms close to coast
- weak swash + strong backwash
- strong backwash removes sediment from the beach
- waves are steep and close together
Weathering
The weakening or decay of rocks in their original place on, or close to, the ground surface. This is usually caused by weather factors such as rainfall and changes in temperature
An example of weathering is mechanical weathering:
Freeze-thaw weathering:
1) water collects in rock crack
2) water freezes + expands, widening crack
3) ice thaws + contracts, so water gets deeper into cracks
4) repeated expansion + contraction —> until rocks split
An example of weathering is chemical weathering:
Carbonation:
Acidic rainwater reacts with CaCO3 in rocks to dissolve it —> cracks in the rocks expand
An example of weathering is biological weathering:
Roots get into small cracks in rock
As the roots grow, cracks become larger
This weakens structure of rock until it breaks away
Burrowing animals also break up rock
Mass movement
The downward movement or sliding of material under the influence of gravity
An example of mass movement is a landslide:
Large blocks of rock slide downhill, usually when rock is saturated
*after heavy rainfall
An example of mass movement is a mudflow:
Saturated soil flows down a slope + there is not enough vegetation to hold the soil in place
*after heavy rainfall
An example of mass movement is a rotational slip:
Saturated soil slumps down a curved surface, usually under the influence of gravity
*after heavy rainfall
E.g. Barton-on-Sea, Dorset Coast
How are headlands and bays formed?
1) Waves attack a discordant coastline (alternating bands of hard + soft rock)
2) Softer rock is eroded by sea much quicker, forming a bay
3) More resistant rock is left jutting out into sea - this is a headland and is more vulnerable to erosion
* concordant coastlines (same type of rock) have fewer headlands + bays
E.g. Studland Bay and Durlston Head, Dorset Coast
Erosion
The wearing away of rock along the coastline
Destructive waves are responsible for erosion on the coastline. There are four types of erosion:
ABRASION
Sediment in waves grind down cliff surfaces like sandpaper
Destructive waves are responsible for erosion on the coastline. There are four types of erosion:
ATTRITION
Waves smash rocks and pebbles on the shore into each other, and they break and become smoother
Destructive waves are responsible for erosion on the coastline. There are four types of erosion:
SOLUTION
Acids in sea water dissolve certain types of rock (e.g. chalk or limestone)
Destructive waves are responsible for erosion on the coastline. There are four types of erosion:
HYDRAULIC ACTION
The sheer power of the waves as they smash against the cliff
Air becomes trapped in the cracks in the rock and causes the rock to break apart
There are different types of transportation…SUSPENSION
fine light material is carried along in the water
There are different types of transportation…SOLUTION
minerals are dissolved in the water and carried along in solution
There are different types of transportation…TRACTION
large boulders and rocks are rolled along the river bed